Hybrid excitation magnetic circuit structure, motor with same and control method thereof

Abstract

The invention provides a hybrid excitation magnetic circuit structure, a motor with the structure and a control method of the motor. According to the hybrid excitation magnetic circuit structure, basic magnetic flux is provided through a permanent magnet rotor assembly, the magnetic flux is dynamically adjusted through an electro-magnetic winding assembly, and superposition enhancement or partial counteracting of a main air gap magnetic field can be achieved only by switching the direction of electro-magnetic current; the output torque of the motor is obviously enhanced; and second-direction current is conducted in a constant power area to counteract part of magnetic flux and expand the speed regulation range of the motor, so that various working condition requirements can be met, and wide-range efficient operation is realized.

Description

Technical Field

[0001] This application relates to the field of electric motors, and in particular to a hybrid excitation magnetic circuit structure, an electric motor with the structure, and a control method thereof. Background Technology

[0002] In the current era of rapid development in automotive electrification, the electric drive system, as the core of vehicle power, directly affects the vehicle's power response, driving range, and operational stability. Among them, permanent magnet motors, with their core advantages of high torque density, high efficiency, and low noise, have become the mainstream choice for automotive electric drive systems, widely used in the drive scenarios of pure electric and hybrid vehicles, providing fundamental support for efficient vehicle operation. Meanwhile, electrically excited motors, by adjusting the excitation current, can flexibly control the excitation magnetic field, achieving magnetization or weakening operations, and have certain application value in some scenarios where magnetic field adjustment is required.

[0003] For automotive electric drive systems, the motor needs to operate stably under different operating conditions, which mainly involves two key operating ranges: the constant torque range and the constant power range. The constant torque range is the low-speed operation stage of the motor, which needs to output stable torque to meet the power requirements of scenarios such as vehicle start-up, acceleration, and hill climbing. The torque density in this range directly determines the low-speed power performance of the vehicle. The constant power range is the high-speed operation stage of the motor, which needs to maintain stable output power, and the torque decreases as the speed increases to meet the needs of scenarios such as high-speed cruising. The operating range and efficiency of this range directly affect the vehicle's high-speed driving ability and range performance.

[0004] However, both existing permanent magnet motors and electrically excited motors have certain technical shortcomings in these two core ranges: In the constant torque range, although permanent magnet motors have a high initial torque density, the inherent magnetic flux characteristics of permanent magnets limit the ability to further increase the magnetic flux intensity through external adjustment, making it difficult to meet the higher torque requirements of scenarios such as heavy-load start-up and steep hill climbing; while electrically excited motors can achieve magnetization by increasing the excitation current, the excitation winding generates additional copper losses, leading to a significant decrease in motor efficiency, and the torque density increase during magnetization is limited, making it difficult to match the initial torque advantage of permanent magnet motors. In the constant power range, permanent magnet motors have limited field weakening capabilities due to the non-adjustable magnetic flux of permanent magnets. When the speed increases to a certain threshold, magnetic circuit saturation is likely to occur, causing the power output to drop prematurely, failing to meet the wide range of high-speed range requirements of vehicles; while electrically excited motors can achieve field weakening by reducing the excitation current to extend the high-speed operating range, the motor torque decays rapidly during field weakening, and the inherently low torque density becomes more pronounced in the high-speed range, making it difficult to balance the high-speed power and energy-saving requirements of vehicles.

[0005] Therefore, how to overcome the technical limitations of the two existing motors and meet the comprehensive requirements of automobiles for high torque in the constant torque region, wide range of constant power region and high efficiency has become an urgent problem to be solved. Summary of the Invention

[0006] The purpose of this application is to provide a hybrid excitation magnetic circuit structure that can meet the requirements of different working conditions, a motor with the structure, and a control method thereof.

[0007] To achieve the above objectives, this application proposes a hybrid excitation magnetic circuit structure, including a stator and a rotor, wherein the stator is disposed inside the rotor, and a main air gap is formed between the stator and the rotor;

[0008] The stator includes a permanent magnet armature winding assembly and an electric excitation winding assembly. The permanent magnet armature winding assembly and the electric excitation winding assembly are coaxially arranged, and the electric excitation winding assembly is connected to both ends of the permanent magnet armature winding assembly.

[0009] The rotor includes an electromagnetic rotor assembly and two sets of permanent magnet rotor assemblies. The electromagnetic rotor assembly and the two sets of permanent magnet rotor assemblies are coaxially arranged. The electromagnetic rotor assembly includes end magnetic conductors distributed on the outside of the two sets of permanent magnet rotor assemblies, and an electromagnetic rotor unit located between the two sets of permanent magnet rotor assemblies.

[0010] When the motor is running in the constant torque region, the first direction current flows through the electric excitation winding assembly. The magnetic field generated by the electric excitation winding starts from the stator side and, under the guidance and constraint of the end magnetic conductor and the electromagnetic rotor unit, passes through the end magnetic conductor on the rotor side, the permanent magnet rotor assembly and the electromagnetic rotor unit, and finally returns to the stator side. The magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap.

[0011] When the motor is operating in the constant power region, a second directional current flows through the electric excitation winding assembly. The magnetic field generated by the electric excitation winding starts from the stator side and, under the guidance and constraint of the electromagnetic rotor unit and the end magnetic conductor, passes through the electromagnetic rotor unit, the permanent magnet rotor assembly and the end magnetic conductor on the rotor side, and finally returns to the stator side. The magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly partially cancel each other out in the main air gap.

[0012] In a further technical solution, the permanent magnet armature winding assembly includes a permanent magnet armature winding and a stator core. The permanent magnet armature winding is wound on the stator core, and the electric excitation winding assembly is connected to both ends of the stator core and located inside the permanent magnet armature winding.

[0013] In a further technical solution, the electric excitation winding assembly includes an electric excitation winding and a winding support retainer. The winding support retainer has a receiving groove on its side, the electric excitation winding is wound in the receiving groove, and the winding support retainer is fixedly connected to the stator core.

[0014] In a further technical solution, the winding support cage is made of a magnetically conductive material.

[0015] In a further technical solution, an insulating element is provided between the winding support cage and the permanent magnet armature winding.

[0016] In a further technical solution, the winding support cage is provided with axial heat dissipation holes, which penetrate the receiving groove and the other side of the winding support cage and are evenly distributed in the circumferential direction; the end magnetic conductor is provided with radial heat dissipation holes, which penetrate the inner and outer circumferential surfaces of the end magnetic conductor and are evenly distributed in the circumferential direction; the area of ​​the axial heat dissipation holes and the radial heat dissipation holes accounts for 6%-8% of the total magnetic conductive area of ​​the winding support cage and the end magnetic conductor.

[0017] In a further technical solution, the permanent magnet rotor assembly includes a rotor core and permanent magnets, with the permanent magnets embedded in the rotor core; the permanent magnets include an N-pole permanent magnet group and an S-pole permanent magnet group, which are evenly distributed alternately along the circumferential direction of the rotor core, and the permanent magnets in the two groups of permanent magnet rotor assemblies are aligned in the axial direction.

[0018] In a further technical solution, the electromagnetic rotor unit includes an electromagnetic yoke ring and salient pole magnets. The salient pole magnets are uniformly distributed along the inner circumferential surface of the electromagnetic yoke ring. The positions of the salient pole magnets correspond to the N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assemblies on both sides. The number of salient pole magnets is equal to, or an approximation of, the number of N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assembly.

[0019] According to a second aspect of this application, a hybrid excitation synchronous motor is provided, including the hybrid excitation magnetic circuit structure as described above, further including a sensor assembly for detecting the motor speed, and a controller electrically connected to the sensor assembly, the permanent magnet armature winding, and the electrically excited winding; the controller is configured to:

[0020] The operating condition of the motor is determined based on the rotational speed detected by the sensor components;

[0021] When the motor is running in the constant torque region, the first direction current is passed through the electric excitation winding, so that the magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap, thereby realizing the magnetization operation in the constant torque region.

[0022] When the motor is running in the constant power region, a second directional current is supplied to the electrically excited winding. The magnetic field generated by the electrically excited winding partially cancels out the magnetic field generated by the permanent magnet rotor assembly in the main air gap, thereby achieving demagnetization operation in the constant power region.

[0023] According to a third aspect of this application, a control method for a hybrid excitation synchronous motor is also provided for controlling the hybrid excitation synchronous motor as described above. The hybrid excitation synchronous motor further includes a current detection component for detecting the armature current in the permanent magnet armature winding. The control method includes: (1) Preset threshold determination: pre-storing the rated speed nn of the motor and the armature current threshold It, wherein the rated speed nn is the critical speed between the constant torque region and the constant power region, and the armature current threshold It is the critical current for determining whether magnetization is required; (2) Real-time signal acquisition: continuously acquiring the current speed nn and the current armature current It of the motor through a sensor component; (3) Operating range determination:

[0024] When n≤n n And I≥I t When the current is determined to be in the constant torque region and magnetization is required, the controller outputs a first-direction current control signal.

[0025] When n≤n n And I t When the current is determined to be in the constant torque region and no magnetization is required, the controller outputs a zero current control signal.

[0026] When n>n n When the system is in the constant power region, it needs to operate with reduced magnetization, and the controller outputs a second-direction current control signal.

[0027] Compared with the prior art, the hybrid excitation magnetic circuit structure, the motor with the structure, and the control method thereof provided in this application have at least the following beneficial effects:

[0028] This structure provides the basic magnetic flux through a permanent magnet rotor assembly and dynamically adjusts the magnetic flux through an electrically excited winding assembly. By simply switching the direction of the electrically excited current, the main air gap magnetic field can be superimposed and enhanced or partially canceled: in the constant torque region (such as low-speed heavy-load scenarios), the first direction current is applied to superimpose the magnetic field and increase the main air gap magnetic flux density, significantly enhancing the motor output torque; in the constant power region (such as high-speed light-load scenarios), the second direction current is applied to cancel out part of the magnetic flux to suppress the rise of back electromotive force and expand the motor speed regulation range, thereby adapting to various operating conditions.

[0029] ​Furthermore, by placing the end magnets and the electric excitation winding assembly on the stator side and the electromagnetic rotor unit on the rotor side, the electric excitation flux can be effectively guided through the main air gap, avoiding the disorderly diffusion of the electric excitation flux to non-target areas, significantly reducing leakage flux loss, and enabling more electric excitation flux to participate in the magnetization and demagnetization cancellation of the main air gap magnetic field, thus significantly improving the sensitivity and response efficiency of the electric excitation to the main air gap magnetic field. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0031] Figure 1 This is an overall structural diagram of the hybrid excitation magnetic circuit structure provided in the embodiments of this application;

[0032] Figure 2 This is a partially cross-sectional view of the hybrid excitation magnetic circuit structure provided in the embodiments of this application;

[0033] Figure 3 This is an exploded view of the hybrid excitation magnetic circuit structure provided in the embodiments of this application;

[0034] Figure 4 This is a schematic cross-sectional view of the stator provided in an embodiment of this application;

[0035] Figure 5 This is an exploded view of the electrically excited winding assembly provided in the embodiments of this application;

[0036] Figure 6 This is a schematic diagram of the main air gap formed by the stator and rotor provided in the embodiments of this application (where red represents the N-pole permanent magnet group and green represents the S-pole permanent magnet group).

[0037] Figure 7 This is an exploded view of the rotor provided in the embodiments of this application (where red represents the permanent magnet group corresponding to the salient pole).

[0038] Figure 8 This is a schematic diagram of the magnetic flux when the electrically excited winding is not energized in the embodiments of this application;

[0039] Figure 9 This is a schematic diagram of the magnetic flux when the electric excitation winding is energized with a first direction current in an embodiment of this application (where the small green arrow represents the electric excitation flux).

[0040] Figure 10This is a schematic diagram of the magnetic flux when the electric excitation winding is energized with a second direction current in an embodiment of this application (where the small red arrow represents the electric excitation flux).

[0041] Figure 11 This is a schematic diagram showing the cooperation relationship between the winding support cage and the end magnet forming a heat dissipation gas channel in an embodiment of this application;

[0042] Figure 12 This is a schematic diagram of the constant torque region and constant power region in the embodiments of this application;

[0043] Figure 13 This is a flowchart of the control method for a hybrid excitation synchronous motor in an embodiment of this application;

[0044] in:

[0045] 1-Stator; 2-Rotor; 3-Main air gap; 11-Permanent magnet armature winding assembly; 111-Permanent magnet armature winding; 112-Stator core; 12-Electrically excited winding assembly; 121-Electrically excited winding; 122-Winding support cage; 123-Receiving slot; 122a-Axial heat dissipation hole; 21-End magnetic conductor; 21a-Radial heat dissipation hole; 22-Permanent magnet rotor assembly; 221-Rotor core; 222-Permanent magnet; 222A-N pole permanent magnet assembly; 222B-S pole permanent magnet assembly; 23-Electromagnetic rotor unit; 231-Electromagnetic yoke ring; 232-Sagittal pole magnetic conductor. Detailed Implementation

[0046] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0047] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0048] Furthermore, the technical solutions of the various embodiments of this application can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application.

[0049] like Figure 1As shown, this embodiment provides a hybrid excitation magnetic circuit structure, including a stator 1 and a rotor 2. The stator 1 is disposed inside the rotor 2, i.e., an outer rotor, inner stator structure. A main air gap 3 is formed between the stator 1 and the rotor 2.

[0050] Figure 2 for Figure 1 A cross-sectional schematic diagram of the hybrid excitation magnetic circuit structure. Figure 3 Here is an exploded view of the hybrid excitation magnetic circuit structure, as shown below. Figure 2 and Figure 3 As shown, the stator 1 includes a permanent magnet armature winding assembly 11 and an electric excitation winding assembly 12. The permanent magnet armature winding assembly 11 and the electric excitation winding assembly 12 are coaxially arranged, and the electric excitation winding assembly 12 is connected to both ends of the permanent magnet armature winding assembly 11.

[0051] The rotor 2 includes an electromagnetic rotor assembly and two sets of permanent magnet rotor assemblies 22. The electromagnetic rotor assembly and the two sets of permanent magnet rotor assemblies 22 are coaxially arranged. The electromagnetic rotor assembly includes end magnetic conductors 21 distributed on the outside of the two sets of permanent magnet rotor assemblies 22, and an electromagnetic rotor unit 23 located between the two sets of permanent magnet rotor assemblies.

[0052] By placing the electric excitation winding assembly 12 on the stator side and the end magnetic conductor 21 and electromagnetic rotor unit 23 on the rotor side, the electric excitation flux can be effectively guided through the main air gap between the stator 1 and the rotor 2, avoiding the disorderly diffusion of the electric excitation flux to non-target areas, greatly reducing leakage flux loss, and enabling more electric excitation flux to participate in the magnetization superposition and demagnetization cancellation of the main air gap magnetic field, thereby improving the sensitivity and response efficiency of the electric excitation to the main air gap magnetic field.

[0053] See Figure 4 The permanent magnet armature winding assembly 11 includes a permanent magnet armature winding 111 and a stator core 112, with the permanent magnet armature winding 111 wound on the stator core 112. The excitation winding assembly 12 is connected to both ends of the stator core 112 and located inside the permanent magnet armature winding 111. By placing the excitation winding assembly 12 in this position, the spare space at the ends of the stator core can be fully utilized, achieving a compact stator structure design.

[0054] Furthermore, by directly connecting the electric excitation winding assembly 12 to the stator core 112, the electric excitation system and the permanent magnet armature system share the same core structure, eliminating the need for a separate excitation core, significantly simplifying the overall structure and reducing material costs. Simultaneously, the stator core 112, as a high-permeability medium, provides a directional magnetic path for the electric excitation magnetic field, guiding the electric excitation flux efficiently to the rotor side while constraining its diffusion into non-target areas, reducing leakage flux losses and improving the regulation efficiency of the electric excitation.

[0055] The structure of the electric excitation winding assembly 12 is as follows: Figure 5As shown, in this embodiment, the electric excitation winding assembly includes an electric excitation winding 121 and a winding support cage 122. The winding support cage 122 has a receiving groove 123 on its side. The electric excitation winding 121 is tightly wound within the receiving groove 123, forming a regular annular excitation unit. The electric excitation winding 121 is coated with a copper wire varnish. The winding support cage 122 is made of a magnetically conductive material to guide more electric excitation flux into the main magnetic circuit. The winding support cage 122, together with the stator core 112, the end magnetic conductor 21, and the electromagnetic rotor unit 23, forms the main magnetic circuit of the electric excitation flux, constraining and guiding the electric excitation flux, thereby reducing leakage flux, significantly reducing flux loss, and improving the regulation efficiency of the electric excitation.

[0056] The axial end of the winding support cage 122 is fixedly connected to the end of the stator core 112 by welding, bolting or other means, which can effectively resist the vibration during motor operation and avoid insulation wear or loosening of the winding due to displacement.

[0057] To prevent the risk of electrical contact between the electrically excited winding assembly 12 and the permanent magnet armature winding assembly 11, a 2mm to 4mm gap can be left between the winding support cage 122 and the permanent magnet armature winding assembly 11, utilizing air as a natural insulating medium. Furthermore, this gap area can be filled with a high-temperature resistant insulating filler (such as silicone rubber insulating paste) to further improve the reliability of electrical insulation. In a possible embodiment, an insulating partition made of a high-strength insulating material (such as glass fiber reinforced epoxy resin) can also be placed between the electrically excited winding assembly 12 and the permanent magnet armature winding assembly 11.

[0058] Because hybrid excitation motors have an additional electrically excited field winding, their total heat generation is higher than that of permanent magnet motors of the same power. Under high excitation demand conditions (such as starting, low speed and high torque, and strong magnetic regulation), the copper losses of the electrically excited field winding will increase significantly, further increasing the total heat dissipation load. In addition, since the electrically excited field winding is installed adjacent to the armature winding, the copper losses of the two will be superimposed, causing local areas at the stator ends to become weak points in heat dissipation.

[0059] Therefore, this embodiment also optimizes the heat dissipation structure of the electric excitation winding.

[0060] In one possible embodiment, the winding support cage 122 is provided with axial heat dissipation holes 122a, which are evenly distributed along the circumferential direction. Part of the heat generated by the electric excitation winding 121 is conducted away through the stator core 112, and part of it is conducted away through the axial heat dissipation holes 122a.

[0061] To further improve heat dissipation, radial heat dissipation holes 21a can be formed along the circumferential direction on the end magnetic conductor 21. For example... Figure 11As shown, when the rotor rotates, the centrifugal force generated by the rotation drives the air to flow outward along the radial heat dissipation holes 21a, thereby forming an airflow extraction effect. This helps to dissipate the heat of the electric excitation winding 121 through the airflow, thereby effectively reducing the operating temperature of the electric excitation component and ensuring the stability and durability of the hybrid excitation structure under high power density operation.

[0062] It should be noted that, in order to minimize the impact on magnetic conductivity, the diameters of the axial heat dissipation holes 122a and 21a should not be too large. Considering both heat dissipation and magnetic conductivity, the area of ​​the axial heat dissipation holes 122a and 21a should preferably account for 6-8% of the total magnetic conductivity area of ​​the winding support cage 122 and the end magnetic conductor 21, such as 6%, 7%, and 8%, respectively. This ensures that a certain heat dissipation effect is achieved without affecting the magnetic conductivity.

[0063] Furthermore, the axial heat dissipation holes 122a and 21a should be located as far away as possible from the main magnetic flux path, i.e., away from the contact surface between the winding support cage 122 and the stator core 112, and the contact surface between the end magnetic conductor 21 and the permanent magnet rotor assembly 22. Therefore, the axial heat dissipation hole 122a can be opened at the corresponding position of the receiving groove 123, and the axial heat dissipation hole 122a can penetrate the receiving groove 123 and the other side of the winding support cage 122, thereby avoiding the contact surface with the stator core 112. The radial heat dissipation hole 21a can be opened through the inner and outer circumferential surfaces of the end magnetic conductor 21, thereby avoiding the contact surface between the end magnetic conductor 21 and the permanent magnet rotor assembly 22. Furthermore, the main magnetic flux path can also be determined through simulation experiments, etc., thereby enabling a more precise determination of the opening position of the heat dissipation holes.

[0064] like Figure 6 and Figure 7 As shown, the permanent magnet rotor assembly 22 includes a rotor core 221 and permanent magnets 222, with the permanent magnets 222 embedded within the rotor core 221. The permanent magnets include an N-pole permanent magnet group 222A and an S-pole permanent magnet group 222B, which are evenly distributed alternately along the circumference of the rotor core 221, and the permanent magnets in the two groups of permanent magnet rotor assemblies are aligned axially. By radially embedding the permanent magnets and distributing them with alternating polarities, more permanent magnet flux can be guided radially through the main air gap 3 to form the main flux, increasing the proportion of the main flux to enhance the external work capability, while ensuring uniform circumferential distribution of the magnetic field and optimizing motor output performance.

[0065] See Figure 7The electromagnetic rotor unit 23 includes an electromagnetic yoke ring 231 and salient pole magnetic conductors 232, which are evenly distributed along the inner circumferential surface of the electromagnetic yoke ring 231. The positions of the salient pole magnetic conductors 232 correspond to the N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assemblies on both sides. In this embodiment, the salient pole magnetic conductors 232 correspond to the N-pole permanent magnet groups (red permanent magnet groups in the figure) in the permanent magnet rotor assemblies on both sides, and the number of them is the same.

[0066] It is important to note that the number of salient pole magnets 232 should be equal to, or an approximation of, the number of N-pole or S-pole permanent magnet groups in the permanent magnet rotor assembly. For example, if there are 8 N-pole permanent magnet groups, the number of salient pole magnets 232 should be 8, 4, 2, or 1. However, since it is difficult to achieve a uniform distribution of the electrically excited magnetic field with only 1 or 2 salient pole magnets 232, it is preferable to use 8 or 4 salient pole magnets 232.

[0067] If the salient pole conductors of the electromagnetic rotor are unevenly distributed or their number does not match the number of pole pairs of the permanent magnets, the coupling efficiency between the electrically excited magnetic flux and the permanent magnet flux will be low, making it impossible to accurately achieve the effect of increasing or decreasing magnetization. By evenly distributing the salient pole conductors and matching their number to the number of pole pairs of the permanent magnets, it can be ensured that the electrically excited magnetic flux can be efficiently coupled with the permanent magnet flux, accurately increasing or decreasing the magnetization of the main magnetic field when energized, and ensuring the adjustment accuracy of the motor under different operating conditions.

[0068] See Figure 8 When the electric excitation winding 121 is not energized, most of the N pole magnetic flux generated by the permanent magnet 222 of the permanent magnet rotor assembly 22 first passes radially through the main air gap 3, through the teeth, yoke and tooth section of the stator core 112, and then returns to the S pole of the permanent magnet 222 through the main air gap 3, forming the main magnetic flux path to do work externally.

[0069] See Figure 9 When a first-direction current flows through the electrically excited winding 121, the magnetic field generated by the electrically excited winding 121 and the magnetic field generated by the permanent magnet rotor assembly 22 are superimposed in the main air gap 3. The permanent magnet flux and the electrically excited flux are connected in parallel to output energy to the outside, thereby increasing the torque density.

[0070] See Figure 10 When a second direction current flows through the electric excitation winding 121, the magnetic field generated by the electric excitation winding 121 and the magnetic field generated by the permanent magnet rotor assembly 22 partially cancel each other out in the main air gap 3, thereby achieving demagnetization operation and expanding the working range.

[0071] The first direction (magnetizing direction) and second direction (demagnetizing direction) of the current in the electrically excited winding 121 must be determined comprehensively by considering the winding direction of the electrically excited winding, the polarity direction of the permanent magnet in the permanent magnet rotor assembly, and Ampere's law. If the winding direction of the electrically excited winding (e.g., changing from clockwise to counterclockwise) or the polarity direction of the permanent magnet is different, the first and second directions of the current in the electrically excited winding 121 will also be different. The core criterion is to ensure that the coupling direction between the electrically excited magnetic field and the permanent magnet magnetic field in the main air gap meets the magnetizing / demagnetizing requirements.

[0072] Most existing synchronous motors use a single excitation method, which cannot simultaneously achieve high torque output in the constant torque region and wide speed regulation in the constant power region. Furthermore, there is a lack of precise control methods for hybrid excitation structures, resulting in limited operating efficiency.

[0073] Therefore, another embodiment of this application also provides a hybrid excitation synchronous motor, including the hybrid excitation magnetic circuit structure described above, and further including a sensor assembly for detecting the motor speed, and a controller electrically connected to the sensor assembly, the permanent magnet armature winding, and the electrically excited winding. The controller determines the motor operating condition based on the speed detected by the sensor assembly, such as... Figure 12 As shown:

[0074] When the motor is running in the constant torque region, the first direction current is applied to the electric excitation winding, so that the magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap, thereby realizing the magnetization operation in the constant torque region.

[0075] When the motor is running in the constant power region, the second direction current is supplied to the control excitation winding. The magnetic field generated by the excitation winding and the magnetic field generated by the permanent magnet rotor assembly are partially canceled in the main air gap, realizing demagnetization operation in the constant power region.

[0076] By integrating the aforementioned hybrid excitation magnetic circuit structure, sensor components, and controller, the excitation mode of the motor can be switched in different operating ranges. In the constant torque region, the magnetization is increased to improve the output torque, and in the constant power region, the magnetization is reduced to expand the speed regulation range, thereby significantly improving the overall operating performance and adaptability of the synchronous motor.

[0077] The sensor assembly used to detect motor speed can be a magneto-electric encoder or a Hall sensor. Its detection end is fixed to the non-output end of the stator and is positioned opposite to the outer circumferential surface of the end magnetic conductor of the outer rotor assembly. The outer circumferential surface of the end magnetic conductor has evenly distributed protruding teeth or magnetic marks along the circumferential direction. Those skilled in the art can also use other methods to measure motor speed.

[0078] Preferably, the hybrid excitation synchronous motor may further include a current detection component for detecting the current in the permanent magnet armature winding, thereby enabling a comprehensive judgment of the motor's operating condition based on the armature current and speed.

[0079] According to another embodiment of this application, a control method for a hybrid excitation synchronous motor is also provided, such as... Figure 13 As shown, it includes: (1) Preset threshold determination: the rated speed n of the motor is stored in advance. n and armature current threshold I t Rated speed n n The critical speed between the constant torque region and the constant power region, armature current threshold I t (2) Real-time signal acquisition: continuously acquire the current motor speed n and current armature current I through sensor components; (3) Operating range determination:

[0080] When n≤n n And I≥I t When the current is determined to be in the constant torque region and magnetization is required, the controller outputs a first-direction current control signal.

[0081] In a possible embodiment, the first directional current control signal is designed to control the magnitude of the current in the excitation winding based on the magnitude of the armature current. For example, a target armature current value can be set, and the magnitude of the current in the excitation winding can be dynamically controlled based on the difference between the actual armature current value and the target armature current value.

[0082] When n≤n n And I t When the current is determined to be in the constant torque region and no magnetization is required, the controller outputs a zero current control signal, meaning that no current flows through the electric excitation winding.

[0083] When n>n n When the system is in the constant power region, it needs to operate with reduced magnetization, and the controller outputs a second-direction current control signal.

[0084] For example, the second directional current control signal can be designed to control the current in the electric excitation winding according to the motor speed. For instance, the current in the electric excitation winding can be controlled to increase linearly as the motor speed increases.

[0085] The above method further subdivides the constant torque region into a high-load state requiring enhanced magnetization and a low-load state not requiring enhanced magnetization. Under high load, enhanced magnetization increases torque, while under low load, electrical excitation is stopped to reduce losses. Through multi-parameter coordinated judgment of speed and armature current, precise division and smooth switching between the constant torque and constant power regions are achieved.

[0086] The above description is merely an embodiment of this application. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of this application, but these improvements all fall within the protection scope of this application.​

Claims

1. A hybrid excitation magnetic circuit structure, applied in an electric motor, characterized in that, The structure includes a stator and a rotor, the stator being disposed inside the rotor, and a main air gap being formed between the stator and the rotor; The stator includes a permanent magnet armature winding assembly and an electric excitation winding assembly. The permanent magnet armature winding assembly and the electric excitation winding assembly are coaxially arranged, and the electric excitation winding assembly is connected to both ends of the permanent magnet armature winding assembly. The rotor includes an electromagnetic rotor assembly and two sets of permanent magnet rotor assemblies. The electromagnetic rotor assembly and the two sets of permanent magnet rotor assemblies are coaxially arranged. The electromagnetic rotor assembly includes end magnetic conductors distributed on the outside of the two sets of permanent magnet rotor assemblies, and an electromagnetic rotor unit located between the two sets of permanent magnet rotor assemblies. When the motor is running in the constant torque region, the first direction current flows through the electric excitation winding assembly. The magnetic field generated by the electric excitation winding starts from the stator side and, under the guidance and constraint of the end magnetic conductor and the electromagnetic rotor unit, passes through the end magnetic conductor on the rotor side, the permanent magnet rotor assembly and the electromagnetic rotor unit, and finally returns to the stator side. The magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap. When the motor is operating in the constant power region, a second directional current flows through the electric excitation winding assembly. The magnetic field generated by the electric excitation winding starts from the stator side and, under the guidance and constraint of the electromagnetic rotor unit and the end magnetic conductor, passes through the electromagnetic rotor unit, the permanent magnet rotor assembly and the end magnetic conductor on the rotor side, and finally returns to the stator side. The magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly partially cancel each other out in the main air gap.

2. The hybrid excitation magnetic circuit structure according to claim 1, characterized in that, The permanent magnet armature winding assembly includes a permanent magnet armature winding and a stator core. The permanent magnet armature winding is wound on the stator core, and the electric excitation winding assembly is connected to both ends of the stator core and located inside the permanent magnet armature winding.

3. The hybrid excitation magnetic circuit structure according to claim 2, characterized in that, The electric excitation winding assembly includes an electric excitation winding and a winding support retainer. The winding support retainer has a receiving groove on its side, and the electric excitation winding is wound in the receiving groove. The winding support retainer is fixedly connected to the stator core.

4. The hybrid excitation magnetic circuit structure according to claim 3, characterized in that, The winding support cage is made of magnetically conductive material.

5. The hybrid excitation magnetic circuit structure according to claim 3, characterized in that, An insulating element is provided between the winding support cage and the permanent magnet armature winding.

6. The hybrid excitation magnetic circuit structure according to claim 3, characterized in that, The winding support cage has axial heat dissipation holes that penetrate the receiving groove and the other side of the winding support cage, and are evenly distributed in the circumferential direction. The end magnetic conductor has radial heat dissipation holes that penetrate the inner and outer circumferential surfaces of the end magnetic conductor, and are evenly distributed in the circumferential direction. The area of ​​the axial heat dissipation holes and the radial heat dissipation holes accounts for 6% to 8% of the total magnetic conductive area of ​​the winding support cage and the end magnetic conductor.

7. The hybrid excitation magnetic circuit structure according to claim 1, characterized in that, The permanent magnet rotor assembly includes a rotor core and permanent magnets, with the permanent magnets embedded in the rotor core. The permanent magnets include an N-pole permanent magnet group and an S-pole permanent magnet group, which are evenly distributed alternately along the circumference of the rotor core, and the permanent magnets in the two groups of permanent magnet rotor assemblies are aligned in the axial direction.

8. The hybrid excitation magnetic circuit structure according to claim 7, characterized in that, The electromagnetic rotor unit includes an electromagnetic yoke ring and salient pole magnets. The salient pole magnets are uniformly distributed along the inner circumferential surface of the electromagnetic yoke ring. The positions of the salient pole magnets correspond to the N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assemblies on both sides. The number of salient pole magnets is equal to, or an approximation of, the number of N-pole permanent magnet groups or S-pole permanent magnet groups in the permanent magnet rotor assembly.

9. A hybrid excitation synchronous motor, characterized in that, Including the hybrid excitation magnetic circuit structure as described in claim 1, it further includes a sensor assembly for detecting motor speed, and a controller electrically connected to the sensor assembly, the permanent magnet armature winding, and the electrically excited winding; the controller is configured to: The operating condition of the motor is determined based on the rotational speed detected by the sensor components; When the motor is running in the constant torque region, the first direction current is passed through the electric excitation winding, so that the magnetic field generated by the electric excitation winding and the magnetic field generated by the permanent magnet rotor assembly are superimposed in the main air gap, thereby realizing the magnetization operation in the constant torque region. When the motor is running in the constant power region, a second directional current is supplied to the electrically excited winding. The magnetic field generated by the electrically excited winding partially cancels out the magnetic field generated by the permanent magnet rotor assembly in the main air gap, thereby achieving demagnetization operation in the constant power region.

10. A control method for a hybrid excitation synchronous motor, used to control the hybrid excitation synchronous motor as described in claim 9, characterized in that, The hybrid excitation synchronous motor further includes a current detection component for detecting the armature current in the permanent magnet armature winding, and the control method includes: Step 1: Determine the preset threshold: Pre-store the rated speed n of the motor. n and armature current threshold I t The rated speed n n The armature current threshold I is the critical speed between the constant torque region and the constant power region. t The critical current used to determine whether magnetization is necessary; Step 2, Real-time signal acquisition: Continuously acquire the current motor speed n and current armature current I through sensor components; Step 3, Determine the operating range: When n≤n n And I≥I t When the current is determined to be in the constant torque region and magnetization is required, the controller outputs a first-direction current control signal. When n≤n n And I t When the current is determined to be in the constant torque region and no magnetization is required, the controller outputs a zero current control signal.​ When n>n n When the system is in the constant power region, it needs to operate with reduced magnetization, and the controller outputs a second-direction current control signal.

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